A Study of Native and Introduced Clupeids in Mobile River Basin Reservoirs
Type of DegreeMaster's Thesis
Fisheries and Allied Aquacultures
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In 2010, Blueback Herring Alosa aestivalis, a nonnative species were first found in Lewis Smith Lake, Alabama. Since this initial discovery, Blueback Herring have been found in several other waters in Alabama including Lake Martin, Yates Lake, and the Lewis Smith Lake dam tailrace. The introduction and population increase of Blueback Herring creates potential for competition with native fish like Threadfin Shad Dorosoma petenense. To quantify the abundance and habitat use of pelagic fishes, hydroacoustic surveys were conducted during July 2016, February 2017, and September 2017 in Lewis Smith Lake, Lake Martin, Bankhead Lake, and Yates Lake. Dissolved oxygen and temperature profiles were recorded down to 40 meters (or the lake bottom) in each lake to determine the available pelagic fish habitat. Summer dissolved oxygen was highest in the epilimnion, depleted at the thermocline, and increased again in the hypolimnion in Lewis Smith Lake and Lake Martin. The layer of cool oxygenated water beneath the thermocline was found to provide suitable habitat for large piscivores during the summer months, and hydroacoustics results suggest that this habitat is used. To assess the comparative forage values of Blueback Herring and Threadfin Shad, their energy densities were quantified using bomb calorimetry of fish from Lewis Smith Lake from April 2016 through December 2017. Caloric densities of Blueback Herring were higher relative to Threadfin Shad for all seasons. These values were incorporated into bioenergetics models to estimate the potential impact on piscivore growth. A positive growth potential was found if piscivores consumed higher proportions of Blueback Herring, however this does not warrant the introduction of this species in other systems.